This invention relates generally to electrostatographic reproduction machines, and more particularly concerns a magnetic roll assembly for use in a development station of such a machine.
In the process of electrostatographic printing, a photoconductive member is uniformly charged and exposed to a light image of an original document. Exposure of the photoconductive member records an electrostatic latent image corresponding to the informational areas contained within the original document. After the electrostatic latent image is recorded on the photoconductive surface, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to form a toner powder image on the photoconductive member which corresponds to the informational areas contained within the original document. This toner powder image is subsequently transferred to a copy sheet and permanently affixed thereto in image configuration.
In electrostatographic reproduction machines, magnetic rolls are frequently employed in the developing station and the cleaning station. Typically, the magnetic roll includes a core and strips of magnets adhesively glued or bonded to the core. At the developing station, a developer material of magnetic carrier granules having toner particles adhering triboelectrically thereto is attracted to the surface of the magnetic roll by the magnetic field generated by the magnetic roll.
The developer material attracted as such is advanced by the surface of the magnetic roll to a position closely adjacent the electrostatic latent image recorded on the photoconductive member. The latent image attracts the toner particles, thus forming a toner powder image on the photoconductive member.
When a magnetic roll is used at the cleaning station, a layer of carrier granules is adhered to the surface of the magnetic roll and is moved therewith. As the layer of carrier granules passes closely adjacent to the photoconductive member, residual toner particles on the photoconductive member are attracted to the layer of carrier granules and are then moved therewith away from the photoconductive member. In this way, residual toner particles are cleaned from the photoconductive member.
Particularly at the development station, proper location of magnets on the magnet roll core is essential to the proper functioning of the development station. This is because incorrect polarity magnets being placed on the core will compromise xerographic performance of the development station.
The conventional use of glue or adhesive bonds to adhere the magnets to the core of the magnetic roll is however a significant problem. Such use of glue does not facilitate rework or remanufacture of the magnet roll assembly without causing damage to the individual magnets or the magnet roll core. Adhering magnets as such onto a magnet roll core is a very time consuming activity and does not encompass any type of foolproofing in terms of the actual location where the magnets are placed onto the magnet roll core.
Typically, placement of each magnet onto the magnet roll core is currently a responsibility of an operator. Consequently, an operator has to reference the part number that is inscribed on each magnet and then cross reference the assembly print to determine where that particular magnet is to be placed on the magnet roll core. This can be problematic when different magnets to be attached or adhered have the same cross sectional geometry and polarity is the only defining difference between magnets. It is therefore very likely that magnets can be glued in the incorrect location if an operator is being rushed to produce parts.
There is therefore a need for a magnetic roll assembly that is easily and correctly assembled, and that can facilitate rework and remanufacturing.
In according to the present invention, there is provided a magnetic roll assembly including an roll core made of a first material and having a longitudinal axis; plural locating members formed of the first material on the outside surface for locating strip magnets; and plural strip magnets located on the plural locating members on the outside surface, the plural strip magnets each having at least first and second surfaces, and a mating feature on one of the at least first and second surfaces mirroring one of the plural locating members for locating and attaching each the plural strip magnets to the roll core, thereby resulting in a magnetic roll assembly that is easily and correctly assembled, and that facilitates rework and remanufacturing.